J.C.
I was co-leader of a GS group that had lots of involved parents too. We ended up having a planning meeting in the beginning of the year where each mother was responsible for planning 1 meeting, top to bottom, where the girls earned a badge. This worked out great for all. No one was spread too thin and each meeting was fabulous because each parent only had 1 meeting to prepare for.
If I were you, I would hold a group parent meeting. See if someone wants to step up a be leader. If no one volunteers, I think you should stick with it for the girls sake. I also think you should delegate many of the planning task too though.
Have a list of what needs to get done for each meeting. Have a signup sheet.
Honestly, when I am leading something, if someone doesn't like the way I am doing it, I remind them that I am a volunteer and that if there is a better way they can certainly help lead the way or put us on the right track.